Functional Avidity of Tumor Antigen-Specific CTL Recognition Directly Correlates with the Stability of MHC/Peptide Multimer Binding to TCR

Tetrameric MHC/peptide complexes are important tools for enumerating, phenotyping, and rapidly cloning Ag-specific T cells. It remains however unclear whether they can reliably distinguish between high and low avidity T cell clones. In this report, tetramers with mutated CD8 binding site selectively stain higher avidity human and murine CTL capable of recognizing physiological levels of Ag. Furthermore, we demonstrate that CD8 binding significantly enhances the avidity as well as the stability of interactions between CTL and cognate tetramers. The use of CD8-null tetramers to identify high avidity CTL provides a tool to compare vaccination strategies for their ability to enhance the frequency of high avidity CTL. Using this technique, we show that DNA priming and vaccinia boosting of HHD A2 transgenic mice fail to selectively expand large numbers of high avidity NY-ESO-1157–165-specific CTL, possibly due to the large amounts of antigenic peptide delivered by the vaccinia virus. Furthermore, development of a protocol for rapid identification of high avidity human and murine T cells using tetramers with impaired CD8 binding provides an opportunity not only to monitor expansion of high avidity T cell responses ex vivo, but also to sort high avidity CTL clones for adoptive T cell transfer therapy.

mentioning

confidence: 99%

High Avidity Antigen-Specific CTL Identified by CD8-Independent Tetramer Staining

Choi

Chen

Wooldridge

et al. 2003

“…Preincubation with anti-CD8 mAb for 30 min followed by removal of unbound mAb by washing and incubation with multimers gave similar results. (21). We also observed that for a given clone, multimers incorporating weak agonist ligands displayed decreased binding efficiency compared with multimers incorporating full agonist ligands and faster off-rates (22).…”

Section: Decreased Pmhc Multimer Binding To Cd8 Does Not Affect Pmhc/mentioning

confidence: 66%

“…As illustrated in Fig. 3A, multimers containing the A2 A245V single mutant showed a highly decreased binding avidity on the MAGE-A10-specific clone 6D1 (21). Reduction in the specific binding avidity of A245V vs wild-type multimers was also observed in the case of Melan-A-specific clone 17 as well as in the case of other MAGE-A10-and Melan-A-specific clones that recognize the peptide with lower avidity (data not shown).…”

Section: Mutations In the A2 ␣3 Cd8-binding Domain Impact On The Bindmentioning

confidence: 66%

Decreased Binding of Peptides-MHC Class I (pMHC) Multimeric Complexes to CD8 Affects Their Binding Avidity for the TCR But Does Not Significantly Impact on pMHC/TCR Dissociation Rate

Dutoit

Guillaume

Ayyoub

et al. 2003

Self Cite

The CD8 coreceptor plays a crucial role in both T cell development in the thymus and in the activation of mature T cells in response to Ag-specific stimulation. In this study we used soluble peptides-MHC class I (pMHC) multimeric complexes bearing mutations in the CD8 binding site that impair their binding to the MHC, together with altered peptide ligands, to assess the impact of CD8 on pMHC binding to the TCR. Our data support a model in which CD8 promotes the binding of TCR to pMHC. However, once the pMHC/TCR complex is formed, the TCR dominates the pMHC/TCR dissociation rates. As a consequence of these molecular interactions, under physiologic conditions CD8 plays a key role in complex formation, resulting in the enhancement of CD8 T cell functions whose specificity, however, is determined by the TCR.

“…3C). According to some previous studies, this could indicate higher avidity of CTLs (17), although this may not always be the case (18).…”

Section: Ctl Priming By Low Mhc Density Aapcs Requires Costimulation mentioning

confidence: 97%

Cutting Edge: Predetermined Avidity of Human CD8 T Cells Expanded on Calibrated MHC/Anti-CD28-Coated Microspheres

Walter

Herrgen

Schoor

et al. 2003

Cytotoxic CD8 T cells are key effectors in the immunotherapy of malignant and viral diseases. However, the lack of efficient methods for their in vitro priming and expansion has become a bottleneck to the development of vaccines and adoptive transfer strategies. Synthetic artificial APCs (aAPCs) are now emerging as an attractive tool for eliciting and expanding CTL responses. We show that, by controlling the MHC density on aAPCs, high- or low-avidity tumor-directed human CTL lines can be raised effectively in vitro if costimulation via CD28 and IL-12 is provided. Compared with low-avidity CTL lines, high-avidity CTLs need 100- to 1000-fold less peptide for activation, bind more MHC tetramers, and, as expected, are superior in recognizing tumor cell lines expressing Ag. We believe that the possibility to raise Ag-specific T cells with predetermined avidity will be crucial for the future use of aAPCs in immunotherapeutical settings.